Iron and cobalt complexes of selected 1,4,7-triaza-3-oxa-1,4,6-heptatrienes or 2,5,8-triaza-1,8-nonadienes are catalysts for the polymerization of ethylene, optionally in the presence of cocatalysts such as alkylaluminum compounds.
Polyethylenes are very important items of commerce, large quantities of various grades of these polymers being produced annually for a large number of uses, such as packaging films and moldings. There are many different methods for making such polymers, including many used commercially, such as free radical polymerization to make low density polyethylene, and many so-called coordination catalysts such as Ziegler-Natta-type and metallocene-type catalysts. Each of these catalyst systems has its advantages and disadvantages, including cost of the polymerization and the particular structure of the polyethylene produced. Due to the importance of polyethylenes, new catalyst systems which are economical and/or produce new types of polyethylenes are constantly being sought.
U.S. Pat. No. 5,955,555, WO98/30612, WO98/38228, WO99/02472 and WO99/12981 (incorporated by reference herein for all purposes) describe the use of iron or cobalt complexes of 2,6-diacylpyridinebisimines or 2,6-pyridinedicarboxaldehydebisimines as catalysts for the polymerization of olefins, mostly of ethylene. These publications describe the preparation of polyethylenes ranging in molecular weight from low molecular weight alpha-olefins and other oligomers to high molecular weight polyethylenes. No mention is made, however, of the use of ligands such as described herein.
R. Roy, et al., Transition Met. Chem. (Weinheim, Ger.), Vol. 9, p. 152-155 (1984) describes cobalt complexes of certain aminodiimines. No mention is made of ligands or metal complexes such as described herein.
This invention concerns a first process for the production of polyethylene, comprising the step of contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., a monomer component comprising ethylene, and an Fe or Co complex of a ligand of the formula 
wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, or R1 and R2 taken together may form a ring;
Ar1 and Ar2 are each independently aryl or substituted aryl;
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or a functional group, provided that any two of R4, R5, R6, R7, R8, R9, R10 and R11 that are vicinal to one another may form a ring;
R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl; and
Ar3 and Ar4 are each independently aryl or substituted aryl.
Also disclosed herein is a second process for the production of polyethylene, comprising the step of contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., a monomer component comprising ethylene, a compound of the formula 
and:
(a) a first compound W, which is a neutral Lewis acid capable of abstracting Xxe2x88x92, an alkyl group or a hydride group from M to form WXxe2x88x92, (WR20)xe2x88x92 or WHxe2x88x92, and which is also capable of transferring an alkyl group or a hydride to M, provided that WXxe2x88x92 is a weakly coordinating anion; or
(b) a combination of second compound which is capable of transferring an alkyl or hydride group to M and a third compound which is a neutral Lewis acid which is capable of abstracting Xxe2x88x92, a hydride or an alkyl group from M to form a weakly coordinating anion;
wherein:
M is Fe or Co;
each X is an anion;
n is an integer so that the total number of negative charges on said anion or anions is equal to the oxidation state of M;
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, or R1 and R2 taken together may form a ring;
Ar1 and Ar2 are each independently aryl or substituted aryl;
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or a functional group, provided that any two of R4, R5, R6, R7, R8, R9, R10 and R11 that are vicinal to one another may form a ring;
R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl;
Ar3 and Ar4 are each independently aryl or substituted aryl; and
R20 is alkyl.
This invention also concerns a third process for the production of polyethylene, comprising the step of contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., a monomer component comprising ethylene, and a compound of the formula 
wherein:
M is Fe or Co;
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, or R1 and R2 taken together may form a ring;
Ar1 and Ar2 are each independently aryl or substituted aryl;
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or a functional group, provided that any two of R4, R5, R6, R7, R8, R9, R10 and R11 that are vicinal to one another may form a ring;
R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl;
Ar3 and Ar4 are each independently aryl or substituted aryl;
Z1 is hydride, alkyl or an anionic ligand into which ethylene can insert;
Y is a neutral ligand capable of being displaced by ethylene, or a vacant coordination site;
Q is a relatively non-coordinating anion;
P is a divalent polyethylene group containing one or more ethylene units; and
Z2 is an end group.
Also disclosed herein is a compound of the formula 
wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, or R1 and R2 taken together may form a ring;
Ar1 and Ar2 are each independently aryl or substituted aryl;
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or a functional group, provided that any two of R4, R5, R6, R7, R8, R9, R10 and R11 that are vicinal to one another may form a ring;
R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl; and
Ar3 and Ar4 are each independently aryl or substituted aryl.
Another compound disclosed herein is a compound of the formula 
wherein:
M is Fe or Co;
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, or R1 and R2 taken together may form a ring;
Ar1 and Ar2 are each independently aryl or substituted aryl;
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or a functional group, provided that any two of R4, R5, R6, R7, R8, R9, R10 and R11 that are vicinal to one another may form a ring;
R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl;
Ar3 and Ar4 are each independently aryl or substituted aryl;
Z1 is hydride or alkyl or any other anionic ligand into which ethylene can insert;
Y is a neutral ligand capable of being displaced by ethylene, or a vacant coordination site;
Q is a relatively non-coordinating anion;
P is a divalent polyethylene group containing one or more ethylene units; and
Z2 is an end group.
A structure drawn such as (II), (IV) and (V) through (X) simply means that the ligand in the square bracket is coordinated to the metal-containing moiety, as indicated by the arrow. Nothing is implied in these formulas about what atoms in the ligand are coordinated to the metal. Without wishing to be bound by any particular theory, it is believed that (I) and (III) are tridentate ligands in coordinating with Fe or Co, and that coordination is effected through the nitrogen atoms shown in formulas (I) and (III).
Herein, certain terms are used. Some of them are:
A xe2x80x9chydrocarbyl groupxe2x80x9d is a univalent group containing only carbon and hydrogen. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylxe2x80x9d herein is meant a hydrocarbyl group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings. Also included in such groups are those in which hydrogen has been completely replaced by another group or element, as in trifluoromethyl.
By xe2x80x9c(inert) functional groupxe2x80x9d herein is meant a group other than hydrocarbyl or substituted hydrocarbyl which is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially interfere with (impede) any process described herein that the compound in which they are present may take part in. Examples of functional groups include, but are not limited to, halo (fluoro, chloro, bromo and iodo), ether such as xe2x80x94OR18 wherein R18 is hydrocarbyl or substituted hydrocarbyl, nitro, silyl, tertiary amino, thioether and ester. In cases in which the functional group may be near a cobalt or iron atom, the functional group should preferably not coordinate to the metal atom more strongly than the usual coordinating groups, that is they should preferably not displace the desired coordinating group.
By an xe2x80x9calkyl aluminum compoundxe2x80x9d is meant a compound in which at least one alkyl group is bound to an aluminum atom. Other groups such as alkoxide, hydride, and halogen may also be bound to aluminum atoms in the compound.
By xe2x80x9cneutral Lewis basexe2x80x9d is meant a compound, which is not an ion, which can act as a Lewis base. Examples of such compounds include ethers, amines, sulfides, and organic nitrites.
By xe2x80x9ccationic Lewis acidxe2x80x9d is meant a cation which can act as a Lewis acid. Examples of such cations are sodium and silver cations.
By xe2x80x9crelatively noncoordinating anionsxe2x80x9d (or xe2x80x9cweakly coordinating anionsxe2x80x9d) is meant those anions as are generally referred to in the art in this manner, and the coordinating ability of such anions is known and has been discussed in the literature, see for instance W. Beck., et al., Chem. Rev., vol. 88 p. 1405-1421 (1988), and S. H. Strauss, Chem. Rev., vol. 93, p. 927-942 (1993), both of which are hereby included by reference. Among such anions are those formed from the aluminum compounds in the immediately preceding paragraph and Xxe2x88x92, including R93AlXxe2x88x92, R92AlClXxe2x88x92, R9AlCl2Xxe2x88x92, and xe2x80x9cR9AlOXxe2x88x92xe2x80x9d, wherein R9 is alkyl. Other useful noncoordinating anions include BAFxe2x88x92{BAF=tetrakis[3,5-bis(trifluoromethyl)phenyl]borate}, SbF631, PF6xe2x88x92, and BF4xe2x88x92, trifluoromethanesulfonate, p-toluenesulfonate, (RfSO2)2Nxe2x88x92, and (C6F5)4Bxe2x88x92.
By an xe2x80x9cempty coordination sitexe2x80x9d is meant a potential coordination site that is not occupied by a ligand. Thus if an ethylene molecule is in the proximity of the empty coordination site, the ethylene molecule may coordinate to the metal atom.
xe2x80x9cArylxe2x80x9d herein also includes heterocyclic rings.
By a xe2x80x9cligand that may add to ethylenexe2x80x9d is meant a ligand coordinated to a metal atom into which an ethylene molecule (or a coordinated ethylene molecule) may insert to start or continue a polymerization. For instance, this may take the form of the reaction (wherein L is a ligand): 
By a xe2x80x9c1,4,7-triaza-3-oxa-1,4,6-heptatrienexe2x80x9d herein is meant a compound having the backbone (with appropriate groups attached of 
while by a xe2x80x9c2,5,8-triaza-1,8-nonadienexe2x80x9d is meant a compound with the backbone (with appropriate groups attached) of 
By an xe2x80x9cend groupxe2x80x9d such as Z2 is meant a group bound to the metal atom into which the first ethylene molecule of the polymer being formed inserted. Typically this will be Z1.
By xe2x80x9cxe2x95x90xe2x80x9d in formulas such as (VI), (VII), (IX) and (X) is meant an ethylene molecule.
By xe2x80x9cpolyethylenexe2x80x9d is, in its broadest sense, meant a polymer based predominantly on ethylene, that is, a polymer in which at least 50 mole percent of the repeat units are dervied from ethylene in the polymerization process. Preferably, the polyethylenes referred to herein have at least 70 mole percent, and more preferably at least 80 mole percent, of the repeat units are derived from ethylene in the polymerization process. By a xe2x80x9chomopolyethylenexe2x80x9d herein is meant a polymer in which substantially all of the repeat units are derived from ethylene in the polymerization process. xe2x80x9cDerived from ethylenexe2x80x9d includes any comonomers generated in situ (either simultaneously with or in series with the actual polymerization) from ethylene such as, for example, those ethylene oligomers formed by the ethylene oligomerization catalyst. Homopolyethylenes are preferred herein.
Iron is a preferred transition metal in all coordination compounds of (I) and (III) (and in processes in which they are used) herein.
Preferred groups in compounds (I) and (III) and their corresponding metal complexes are:
R1 and R2 are each independently hydrogen or alkyl containing 1 to 4 carbon atoms, more preferably both R1 and R2 are hydrogen or methyl; and/or
R1 and R2 taken together form a ring, more preferably a carbocyclic ring, and especially preferably R1 and R2 taken together are 
R3 is aryl, substituted aryl or alkyl, more preferably aryl, substituted aryl or alkyl containing 1 to 4 carbon atoms, especially preferably phenyl, t-butyl or methyl; and/or
Ar1 and Ar2 are 2-substituted (with no substitution in the 6 position) or 2,6-disubstituted phenyl with substitution optional at any other ring position; and more preferably the substituents in the 2 and 6 (when present) positions are alkyl containing 1 to 4 carbon atoms or hydrogen; and/or
R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 are each hydrogen; and/or
R12 and R13 are hydrogen; and/or
R14 is hydrogen or hydrocarbyl, more preferably hydrogen or alkyl, especially preferably methyl or hydrogen, and highly preferably hydrogen; and/or
Ar3 and Ar4 are 2-substituted (with no substitution in the 6 position) or 2,6-disubstituted phenyl with substitution optional at any other ring position; and more preferably the substituents in the 2 and 6 (when present) positions are alkyl containing 1 to 4 carbon atoms or hydrogen; and/or
Ar3 and Ar4 are 9-anthracenyl; and/or
Ar3 and Ar4 are the same.
In compounds in which it occurs, it is preferred that X is halo (especially chloride or bromide), carboxylate such as acetate, citrate, cyclohexane butyrate, 2-ethylhexanoate, stearate and oxalate, acetylacetonate, benzoylacetonate, hexafluoroacetylacetonate, hydroxide, 2,2,6,6-tetramethyl-3,5-heptanedionate, p-toluenesulfonate, ethoxide, i-propoxide, trifluoroacetylacetonate, and tetrafluoroborate. Especially preferred anions X are halide, carboxylate and acetylacetonate.
The iron and cobalt in the complexes may be in the +2 or +3 oxidation state, and +2 is preferred.
Ar1, Ar2, Ar3, and Ar4 may also each independently be aryl, substituted aryl, hydrocarbyl or substituted hydrocarbyl provided that in the hydrocarbyl or substituted hydrocarbyl groups the carbon atom bound to the imino nitrogen is bound to at least two other carbon atoms. It is preferred that Ar1, Ar2, Ar3, and Ar4 are each independently aryl or substituted aryl.
Specific preferred compounds for (I) and (III), and their corresponding Fe and Co complexes, are: 
Included within the meaning of compounds (VII) and (X) are agostic structures in which the ethylene is replaced as a ligand by coordination to xe2x80x94PZ2 to form an agostic xe2x80x9cbidentatexe2x80x9d ligand.
In the second polymerization process described herein an iron or cobalt complex (II) or (IV) is contacted with ethylene and a neutral Lewis acid W capable of abstracting Xxe2x88x92, hydride or alkyl from (II) or (IV) to form a weakly coordinating anion, and must alkylate or be capable of adding a hydride ion to the metal atom, or an additional alkylating agent or an agent capable of adding a hydride anion to the metal atom must be present. The neutral Lewis acid is originally uncharged (i.e., not ionic). Suitable neutral Lewis acids include SbF5, Ar3B (wherein Ar is aryl), and BF3. In those instances in which (II) or (IV) (and similar catalysts which require the presence of a neutral Lewis acid), does not contain an alkyl or hydride group already bonded to the metal atom, the neutral Lewis acid or a cationic Lewis or Bronsted acid also alkylates or adds a hydride to the metal or a separate alkylating or hydriding agent is present, i.e., causes an alkyl,group or hydride to become bonded to the metal atom.
It is preferred that R20contains 1 to 4 carbon atoms, and more preferred that R20 is methyl or ethyl.
For instance, alkyl aluminum compounds (see next paragraph) may alkylate (II). However, not all alkyl aluminum compounds may be strong enough Lewis acids to abstract Xxe2x88x92 or an alkyl group from the metal atom. In that case a separate Lewis acid strong enough to do the abstraction must be present.
A preferred neutral Lewis acid, which can alkylate the metal, is a selected alkyl aluminum compound, such as R193Al, R19AlCl2, R192AlCl, and xe2x80x9cR19AlOxe2x80x9d (alkylaluminoxanes), wherein R19 is alkyl containing 1 to 25 carbon atoms, preferably 1 to 4 carbon atoms. Suitable alkyl aluminum compounds include methylaluminoxane (which is an oligomer with the general formula [MeAlO]n), optionally modified with minor amounts of other alkyl groups, (C2H5)2AlCl, C2H5AlCl2, and [(CH3)2CHCH2]3Al.
Metal hydrides such as NaBH4 may be used to bond hydride groups to the metal M.
The polymerization catalysts and catalyst systems described herein may produce polyethylene in a variety of molecular weights and molecular weight distributions. The molecular weights of these polymers may vary from compounds containing only a few ethylene molecules (e.g., oligomers) to polymers having molecular weights in the hundreds of thousands, and even higher. The molecular weight of the polymer produced in any particular polymerization process will depends on the process conditions used, and on the compound [such as (I) and (III)] which is used in the polymerization catalyst system. In one form of xe2x80x9cchain transferxe2x80x9d in the polymerization process it is believed that an olefinic group is formed on the end of the polymer chain (see Examples 23-44, wherein Mn is measured by 1H NMR assuming all olefinic groups are end groups). If the olefinic group is on the end of a linear polymer chain that happens to be a relatively short polymer chain (say containing 4 to about 30 carbon atoms) the product is sometimes termed a linear xcex1-olefin (LAO). LAOs are important items of commerce, useful as monomers and as chemical intermediates for items such as detergents and lubricating oils. For making LAOs it is preferred that in (I) and (III), and their Fe and Co complexes, that Ar1 and Ar2are independently phenyl or 2-substituted phenyl, or Ar3 and Ar4are independently phenyl or 2-substituted phenyl, for example 2-methylphenyl or 2-i-propylphenyl.
Compounds such as (I) may be made by reacting an appropriate dicarbonyl compound with one mole of hydroxylamine to form the monooxime. This oxime containing a second carbonyl group is then reacted with an arylamine to form the imine-oxime. The anion of the oxime is then formed by reaction with a strong base, such as an alkali metal hydride, followed by reaction with an appropriate chloroimine to form (I). The chloroimines are made by reaction of the appropriate amide with a chlorinating agent such as PCl5. These various reactions are illustrated herein in Examples 1-9.
(III) may be made by the reaction of the appropriate diethylenetriamine (or appropriate analog) with a carbonyl substituted aryl compound.
Complexes of (I) or (III) with Fe or Co may be made by methods known in the art, see for instance previously incorporated U.S. Pat. No. 5,955,555, wherein the preparation of Fe and Co complexes of pyridinebisimines are described. Analogous methods may be used to make complexes of (I) and (III).
In all the polymerization processes herein, the temperature at which the polymerization is carried out is about xe2x88x92100xc2x0 C. to about +200xc2x0 C., preferably about 0xc2x0 C. to about 150xc2x0 C., more preferably about 25xc2x0 C. to about 100xc2x0 C. The ethylene concentration at which the polymerization is carried out is not critical, atmospheric pressure to about 275 MPa being a suitable range for ethylene.
The polymerization processes herein may be run in the presence of various liquids, particularly aprotic organic liquids. The catalyst system, ethylene, and polyethylene may be soluble or insoluble in these liquids, but obviously these liquids should not prevent the polymerization from occurring. Suitable liquids include alkanes, cycloalkanes, selected halogenated hydrocarbons, selected aromatic halogenated hydrocarbons, and aromatic hydrocarbons. Hydrocarbons are the preferred solvent. Specific useful solvents include hexane, heptane, toluene, benzene, chlorobenzene, methylene chloride, 1,2,4-trichorobenzene, p-xylene, and cyclohexane.
The catalysts herein may be xe2x80x9cheterogenizedxe2x80x9d by coating or otherwise attaching them to solid supports, such as silica or alumina. Where an active catalyst species is formed by reaction with a compound such as an alkylaluminum compound, a support on which the alkylaluminum compound is first coated or otherwise attached is contacted with the iron or cobalt compound precursor to form a catalyst system in which the active iron or cobalt catalyst is xe2x80x9cattachedxe2x80x9d to the solid support. These supported catalysts may be used in polymerizations in organic liquids, as described in the immediately preceding paragraph. They may also be used in so-called gas phase polymerizations in which the ethylene being polymerized is added to the polymerization as a gas and no liquid supporting phase is present.
The polymerization processes described herein may be run in any manner common for coordination olefin polymerization processes, such as batch, semi-batch, and continuous. Processes applicable generally to Ziegler-Natta and metallocene-type polymerization catalysts may also be used in the present processes. The processes may be run in solution, slurry or gas phases.
It is believed that usually the homopolyethylene produced by the present polymerization processes are fairly linear polymers with little branching.
It is known that certain transition metal containing polymerization catalysts are especially useful in varying the branching in polyolefins made with them, see for instance U.S. Pat. Nos. 5,714,556, 5,880,241, WO98/30610 and WO98/30609 (all of which are incorporated by reference herein for all purposes). It is also known that blends of distinct polymers, that vary for instance in branching, molecular weight, and/or molecular weight distribution, may have advantageous properties compared to xe2x80x9csinglexe2x80x9d polymers. For instance it is known that polymers with broad or bimodal molecular weight distributions may be melt processed (be shaped) more easily than narrower molecular weight distribution polymers. Similarly, thermoplastics such as crystalline polymers may often be toughened by blending with elastomeric polymers.
Therefore, methods of producing polymers which inherently produce polymer blends are useful especially if a later separate (and expensive) polymer mixing step can be avoided. However in such polymerizations one should be aware that two different catalysts may interfere with one another, or interact in such a way as to give a single polymer.
In such a process the catalysts disclosed herein can be termed the first active polymerization catalyst. Monomers useful with these catalysts are those described (and also preferred) above.
A second active polymerization catalyst (and optionally one or more others) is used in conjunction with the first active polymerization catalyst. The second active polymerization catalyst may be another late transition metal catalyst, for example as described in previously incorporated WO98/30610, WO98/30609, U.S. Pat. Nos. 5,714,556, 5,880,241 and U.S. Pat. No. 5,955,555.
Other useful types of catalysts may also be used for the second active polymerization catalyst. For instance so-called Ziegler-Natta and/or metallocene-type catalysts may also be used. These types of catalysts are well known in the polyolefin field, see for instance Angew. Chem., Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and U.S. Pat. No. 5,198,401 for information about metallocene-type catalysts, and J. Boor Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press, New York, 1979 for information about Ziegler-Natta-type catalysts, all of which are hereby included by reference. Many of the useful polymerization conditions for all of these types of catalysts and the first active polymerization catalysts coincide, so conditions for the polymerizations with first and second active polymerization catalysts are easily accessible. Oftentimes the xe2x80x9cco-catalystxe2x80x9d or xe2x80x9cactivatorxe2x80x9d is needed for metallocene or Ziegler-Natta-type polymerizations. In many instances the same compound, such as an alkylaluminum compound, may be used as an xe2x80x9cactivatorxe2x80x9d for some or all of these various polymerization catalysts.
Suitable catalysts for the second polymerization catalyst also include metallocene-type catalysts, as described in U.S. Pat. No. 5,324,800 and EP-0129368; particularly advantageous are bridged bis-indenyl metallocenes, for instance as described in U.S. Pat. No. 5,145,819 and EP-A-0485823. Another class of suitable catalysts comprises the well-known constrained geometry catalysts, as described in EP-A-0416815, EP-A-0420436, EP-A-0671404, EP-A-0643066 and WO91/04257. Finally, the class of transition metal complexes described in WO96/13529 can be used. All of the above-mentioned publications are hereby included by reference herein.
In one preferred process described herein the first olefin(s) [the monomer(s), usually ethylene, polymerized by the first active polymerization catalyst] and second olefin(s) [the monomer(s) polymerized by the second active polymerization catalyst] are identical, and preferred olefins in such a process are the same as described immediately above. The first and/or second olefins may also be a single olefin or a mixture of olefins to make a copolymer. Again it is preferred that they be identical particularly in a process in which polymerization by the first and second active polymerization catalysts make polymer simultaneously.
In some processes herein the first active polymerization catalyst may polymerize a monomer that may not be polymerized by said second active polymerization catalyst, and/or vice versa. In that instance two chemically distinct polymers may be produced. In another scenario two monomers would be present, with one polymerization catalyst producing a copolymer, and the other polymerization catalyst producing a homopolymer, or two copolymers may be produced which vary in the molar proportion or repeat units from the various monomers. Other analogous combinations will be evident to the artisan.
In another variation of this process one of the polymerization catalysts makes an oligomer of an olefin, preferably ethylene, which oligomer has the formula R70CHxe2x95x90CH2, wherein R70 is n-alkyl, preferably with an even number of carbon atoms. The other polymerization catalyst in the process then (co)polymerizes this olefin, either by itself or preferably with at least one other olefin, preferably ethylene, to form a branched polyolefin. Preparation of the oligomer (which is sometimes called an xcex1-olefin) by a second active polymerization-type of catalyst can be found in previously incorporated U.S. Pat. No. 5,880,241, and WO99/02472 (also incorporated by reference herein for all purposes).
Likewise, conditions for such polymerizations, using catalysts of the second active polymerization type, will also be found in the appropriate above mentioned references.
Two chemically different active polymerization catalysts are used in this polymerization process. The first active polymerization catalyst is described in detail above. The second active polymerization catalyst may also meet the limitations of the first active polymerization catalyst, but must be chemically distinct. For instance, it may have a different transition metal present, and/or utilize a different type of ligand and/or the same type of ligand which differs in structure between the first and second active polymerization catalysts. In one preferred process, the ligand type and the metal are the same, but the ligands differ in their substituents.
Included within the definition of two active polymerization catalysts are systems in which a single polymerization catalyst is added together with another ligand, preferably the same type of ligand, which can displace the original ligand coordinated to the metal of the original active polymerization catalyst, to produce in situ two different polymerization catalysts.
The molar ratio of the first active polymerization catalyst to the second active polymerization catalyst used will depend on the ratio of polymer from each catalyst desired, and the relative rate of polymerization of each catalyst under the process conditions. For instance, if one wanted to prepare a xe2x80x9ctoughenedxe2x80x9d thermoplastic polyethylene that contained 80% crystalline polyethylene and 20% rubbery polyethylene, and the rates of polymerization of the two catalysts were equal, then one would use a 4:1 molar ratio of the catalyst that gave crystalline polyethylene to the catalyst that gave rubbery polyethylene. More than two active polymerization catalysts may also be used if the desired product is to contain more than two different types of polymer.
The polymers made by the first active polymerization catalyst and the second active polymerization catalyst may be made in sequence, i.e., a polymerization with one (either first or second) of the catalysts followed by a polymerization with the other catalyst, as by using two polymerization vessels in series. However it is preferred to carry out the polymerization using the first and second active polymerization catalysts in the same vessel(s), i.e., simultaneously. This is possible because in most instances the first and second active polymerization catalysts are compatible with each other, and they produce their distinctive polymers in the other catalyst""s presence. Any of the processes applicable to the individual catalysts may be used in this polymerization process with 2 or more catalysts, i.e., gas phase, liquid phase, continuous, batch etc.
The polymers produced by this xe2x80x9cmixed catalystxe2x80x9d process may vary in molecular weight and/or molecular weight distribution and/or melting point and/or level of crystallinity, and/or glass transition temperature and/or other factors. For copolymers the polymers may differ in ratios of comonomers if the different polymerization catalysts polymerize the monomers present at different relative rates. The polymers produced are useful as molding and extrusion resins and in films as for packaging. They may have advantages such as improved melt processing, toughness and improved low temperature properties.
Hydrogen may be used to lower the molecular weight of polyethylene produced in the first, second or third processes, or any other processes mentioned above in which the present transition metal complexes are used. It is preferred that the amount of hydrogen present be about 0.01 to about 50 mole percent of the ethylene present, preferably about 1 to about 20 mole percent. The relative concentrations of ethylene and hydrogen may be regulated by their partial pressures.
Included herein within the definitions of all the polymerization processes are mixtures of starting materials that lead to the formation in situ of the transition metal compounds specified in all of the polymerization processes.
In the first, second and third polymerization process, and other polymerization processes herein one or more olefins of the formula R15CHxe2x95x90CH2 may be homopolymerized or copolymerized with each and/or with ethylene using the iron and cobalt complex of (I) and (III), as described herein. Similar (to ethylene polymerization) process conditions may be used to carry out these polymerizations.
The polymers produced by the present processes are useful as molding resins, for films and other uses. End use areas include industrial and consumer parts and packaging.
In the Examples, the following abbreviations are used:
Arxe2x80x94aryl
Etxe2x80x94ethyl
GPCxe2x80x94gel permeation chromatography
Mexe2x80x94methyl
MIxe2x80x94melt index
PExe2x80x94polyethylene
Phxe2x80x94phenyl
RTxe2x80x94room temperature
TCBxe2x80x941,2,4-trichlorobenzene
THFxe2x80x94tetrahydrofuran
TOxe2x80x94turnovers